diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kernel/i8259.c | 457 |
1 files changed, 457 insertions, 0 deletions
diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c new file mode 100644 index 000000000..4c9f559e1 --- /dev/null +++ b/arch/x86/kernel/i8259.c @@ -0,0 +1,457 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/linkage.h> +#include <linux/errno.h> +#include <linux/signal.h> +#include <linux/sched.h> +#include <linux/ioport.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/timex.h> +#include <linux/random.h> +#include <linux/init.h> +#include <linux/kernel_stat.h> +#include <linux/syscore_ops.h> +#include <linux/bitops.h> +#include <linux/acpi.h> +#include <linux/io.h> +#include <linux/delay.h> +#include <linux/pgtable.h> + +#include <linux/atomic.h> +#include <asm/timer.h> +#include <asm/hw_irq.h> +#include <asm/desc.h> +#include <asm/apic.h> +#include <asm/i8259.h> + +/* + * This is the 'legacy' 8259A Programmable Interrupt Controller, + * present in the majority of PC/AT boxes. + * plus some generic x86 specific things if generic specifics makes + * any sense at all. + */ +static void init_8259A(int auto_eoi); + +static bool pcat_compat __ro_after_init; +static int i8259A_auto_eoi; +DEFINE_RAW_SPINLOCK(i8259A_lock); + +/* + * 8259A PIC functions to handle ISA devices: + */ + +/* + * This contains the irq mask for both 8259A irq controllers, + */ +unsigned int cached_irq_mask = 0xffff; + +/* + * Not all IRQs can be routed through the IO-APIC, eg. on certain (older) + * boards the timer interrupt is not really connected to any IO-APIC pin, + * it's fed to the master 8259A's IR0 line only. + * + * Any '1' bit in this mask means the IRQ is routed through the IO-APIC. + * this 'mixed mode' IRQ handling costs nothing because it's only used + * at IRQ setup time. + */ +unsigned long io_apic_irqs; + +static void mask_8259A_irq(unsigned int irq) +{ + unsigned int mask = 1 << irq; + unsigned long flags; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + cached_irq_mask |= mask; + if (irq & 8) + outb(cached_slave_mask, PIC_SLAVE_IMR); + else + outb(cached_master_mask, PIC_MASTER_IMR); + raw_spin_unlock_irqrestore(&i8259A_lock, flags); +} + +static void disable_8259A_irq(struct irq_data *data) +{ + mask_8259A_irq(data->irq); +} + +static void unmask_8259A_irq(unsigned int irq) +{ + unsigned int mask = ~(1 << irq); + unsigned long flags; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + cached_irq_mask &= mask; + if (irq & 8) + outb(cached_slave_mask, PIC_SLAVE_IMR); + else + outb(cached_master_mask, PIC_MASTER_IMR); + raw_spin_unlock_irqrestore(&i8259A_lock, flags); +} + +static void enable_8259A_irq(struct irq_data *data) +{ + unmask_8259A_irq(data->irq); +} + +static int i8259A_irq_pending(unsigned int irq) +{ + unsigned int mask = 1<<irq; + unsigned long flags; + int ret; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + if (irq < 8) + ret = inb(PIC_MASTER_CMD) & mask; + else + ret = inb(PIC_SLAVE_CMD) & (mask >> 8); + raw_spin_unlock_irqrestore(&i8259A_lock, flags); + + return ret; +} + +static void make_8259A_irq(unsigned int irq) +{ + disable_irq_nosync(irq); + io_apic_irqs &= ~(1<<irq); + irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq); + irq_set_status_flags(irq, IRQ_LEVEL); + enable_irq(irq); + lapic_assign_legacy_vector(irq, true); +} + +/* + * This function assumes to be called rarely. Switching between + * 8259A registers is slow. + * This has to be protected by the irq controller spinlock + * before being called. + */ +static inline int i8259A_irq_real(unsigned int irq) +{ + int value; + int irqmask = 1<<irq; + + if (irq < 8) { + outb(0x0B, PIC_MASTER_CMD); /* ISR register */ + value = inb(PIC_MASTER_CMD) & irqmask; + outb(0x0A, PIC_MASTER_CMD); /* back to the IRR register */ + return value; + } + outb(0x0B, PIC_SLAVE_CMD); /* ISR register */ + value = inb(PIC_SLAVE_CMD) & (irqmask >> 8); + outb(0x0A, PIC_SLAVE_CMD); /* back to the IRR register */ + return value; +} + +/* + * Careful! The 8259A is a fragile beast, it pretty + * much _has_ to be done exactly like this (mask it + * first, _then_ send the EOI, and the order of EOI + * to the two 8259s is important! + */ +static void mask_and_ack_8259A(struct irq_data *data) +{ + unsigned int irq = data->irq; + unsigned int irqmask = 1 << irq; + unsigned long flags; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + /* + * Lightweight spurious IRQ detection. We do not want + * to overdo spurious IRQ handling - it's usually a sign + * of hardware problems, so we only do the checks we can + * do without slowing down good hardware unnecessarily. + * + * Note that IRQ7 and IRQ15 (the two spurious IRQs + * usually resulting from the 8259A-1|2 PICs) occur + * even if the IRQ is masked in the 8259A. Thus we + * can check spurious 8259A IRQs without doing the + * quite slow i8259A_irq_real() call for every IRQ. + * This does not cover 100% of spurious interrupts, + * but should be enough to warn the user that there + * is something bad going on ... + */ + if (cached_irq_mask & irqmask) + goto spurious_8259A_irq; + cached_irq_mask |= irqmask; + +handle_real_irq: + if (irq & 8) { + inb(PIC_SLAVE_IMR); /* DUMMY - (do we need this?) */ + outb(cached_slave_mask, PIC_SLAVE_IMR); + /* 'Specific EOI' to slave */ + outb(0x60+(irq&7), PIC_SLAVE_CMD); + /* 'Specific EOI' to master-IRQ2 */ + outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD); + } else { + inb(PIC_MASTER_IMR); /* DUMMY - (do we need this?) */ + outb(cached_master_mask, PIC_MASTER_IMR); + outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */ + } + raw_spin_unlock_irqrestore(&i8259A_lock, flags); + return; + +spurious_8259A_irq: + /* + * this is the slow path - should happen rarely. + */ + if (i8259A_irq_real(irq)) + /* + * oops, the IRQ _is_ in service according to the + * 8259A - not spurious, go handle it. + */ + goto handle_real_irq; + + { + static int spurious_irq_mask; + /* + * At this point we can be sure the IRQ is spurious, + * lets ACK and report it. [once per IRQ] + */ + if (!(spurious_irq_mask & irqmask)) { + printk_deferred(KERN_DEBUG + "spurious 8259A interrupt: IRQ%d.\n", irq); + spurious_irq_mask |= irqmask; + } + atomic_inc(&irq_err_count); + /* + * Theoretically we do not have to handle this IRQ, + * but in Linux this does not cause problems and is + * simpler for us. + */ + goto handle_real_irq; + } +} + +struct irq_chip i8259A_chip = { + .name = "XT-PIC", + .irq_mask = disable_8259A_irq, + .irq_disable = disable_8259A_irq, + .irq_unmask = enable_8259A_irq, + .irq_mask_ack = mask_and_ack_8259A, +}; + +static char irq_trigger[2]; +/** + * ELCR registers (0x4d0, 0x4d1) control edge/level of IRQ + */ +static void restore_ELCR(char *trigger) +{ + outb(trigger[0], 0x4d0); + outb(trigger[1], 0x4d1); +} + +static void save_ELCR(char *trigger) +{ + /* IRQ 0,1,2,8,13 are marked as reserved */ + trigger[0] = inb(0x4d0) & 0xF8; + trigger[1] = inb(0x4d1) & 0xDE; +} + +static void i8259A_resume(void) +{ + init_8259A(i8259A_auto_eoi); + restore_ELCR(irq_trigger); +} + +static int i8259A_suspend(void) +{ + save_ELCR(irq_trigger); + return 0; +} + +static void i8259A_shutdown(void) +{ + /* Put the i8259A into a quiescent state that + * the kernel initialization code can get it + * out of. + */ + outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ + outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ +} + +static struct syscore_ops i8259_syscore_ops = { + .suspend = i8259A_suspend, + .resume = i8259A_resume, + .shutdown = i8259A_shutdown, +}; + +static void mask_8259A(void) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + + outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ + outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ + + raw_spin_unlock_irqrestore(&i8259A_lock, flags); +} + +static void unmask_8259A(void) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + + outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */ + outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */ + + raw_spin_unlock_irqrestore(&i8259A_lock, flags); +} + +static int probe_8259A(void) +{ + unsigned char new_val, probe_val = ~(1 << PIC_CASCADE_IR); + unsigned long flags; + + /* + * If MADT has the PCAT_COMPAT flag set, then do not bother probing + * for the PIC. Some BIOSes leave the PIC uninitialized and probing + * fails. + * + * Right now this causes problems as quite some code depends on + * nr_legacy_irqs() > 0 or has_legacy_pic() == true. This is silly + * when the system has an IO/APIC because then PIC is not required + * at all, except for really old machines where the timer interrupt + * must be routed through the PIC. So just pretend that the PIC is + * there and let legacy_pic->init() initialize it for nothing. + * + * Alternatively this could just try to initialize the PIC and + * repeat the probe, but for cases where there is no PIC that's + * just pointless. + */ + if (pcat_compat) + return nr_legacy_irqs(); + + /* + * Check to see if we have a PIC. Mask all except the cascade and + * read back the value we just wrote. If we don't have a PIC, we + * will read 0xff as opposed to the value we wrote. + */ + raw_spin_lock_irqsave(&i8259A_lock, flags); + + outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ + outb(probe_val, PIC_MASTER_IMR); + new_val = inb(PIC_MASTER_IMR); + if (new_val != probe_val) { + printk(KERN_INFO "Using NULL legacy PIC\n"); + legacy_pic = &null_legacy_pic; + } + + raw_spin_unlock_irqrestore(&i8259A_lock, flags); + return nr_legacy_irqs(); +} + +static void init_8259A(int auto_eoi) +{ + unsigned long flags; + + i8259A_auto_eoi = auto_eoi; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + + outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ + + /* + * outb_pic - this has to work on a wide range of PC hardware. + */ + outb_pic(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */ + + /* ICW2: 8259A-1 IR0-7 mapped to ISA_IRQ_VECTOR(0) */ + outb_pic(ISA_IRQ_VECTOR(0), PIC_MASTER_IMR); + + /* 8259A-1 (the master) has a slave on IR2 */ + outb_pic(1U << PIC_CASCADE_IR, PIC_MASTER_IMR); + + if (auto_eoi) /* master does Auto EOI */ + outb_pic(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR); + else /* master expects normal EOI */ + outb_pic(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR); + + outb_pic(0x11, PIC_SLAVE_CMD); /* ICW1: select 8259A-2 init */ + + /* ICW2: 8259A-2 IR0-7 mapped to ISA_IRQ_VECTOR(8) */ + outb_pic(ISA_IRQ_VECTOR(8), PIC_SLAVE_IMR); + /* 8259A-2 is a slave on master's IR2 */ + outb_pic(PIC_CASCADE_IR, PIC_SLAVE_IMR); + /* (slave's support for AEOI in flat mode is to be investigated) */ + outb_pic(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR); + + if (auto_eoi) + /* + * In AEOI mode we just have to mask the interrupt + * when acking. + */ + i8259A_chip.irq_mask_ack = disable_8259A_irq; + else + i8259A_chip.irq_mask_ack = mask_and_ack_8259A; + + udelay(100); /* wait for 8259A to initialize */ + + outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */ + outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */ + + raw_spin_unlock_irqrestore(&i8259A_lock, flags); +} + +/* + * make i8259 a driver so that we can select pic functions at run time. the goal + * is to make x86 binary compatible among pc compatible and non-pc compatible + * platforms, such as x86 MID. + */ + +static void legacy_pic_noop(void) { }; +static void legacy_pic_uint_noop(unsigned int unused) { }; +static void legacy_pic_int_noop(int unused) { }; +static int legacy_pic_irq_pending_noop(unsigned int irq) +{ + return 0; +} +static int legacy_pic_probe(void) +{ + return 0; +} + +struct legacy_pic null_legacy_pic = { + .nr_legacy_irqs = 0, + .chip = &dummy_irq_chip, + .mask = legacy_pic_uint_noop, + .unmask = legacy_pic_uint_noop, + .mask_all = legacy_pic_noop, + .restore_mask = legacy_pic_noop, + .init = legacy_pic_int_noop, + .probe = legacy_pic_probe, + .irq_pending = legacy_pic_irq_pending_noop, + .make_irq = legacy_pic_uint_noop, +}; + +struct legacy_pic default_legacy_pic = { + .nr_legacy_irqs = NR_IRQS_LEGACY, + .chip = &i8259A_chip, + .mask = mask_8259A_irq, + .unmask = unmask_8259A_irq, + .mask_all = mask_8259A, + .restore_mask = unmask_8259A, + .init = init_8259A, + .probe = probe_8259A, + .irq_pending = i8259A_irq_pending, + .make_irq = make_8259A_irq, +}; + +struct legacy_pic *legacy_pic = &default_legacy_pic; +EXPORT_SYMBOL(legacy_pic); + +static int __init i8259A_init_ops(void) +{ + if (legacy_pic == &default_legacy_pic) + register_syscore_ops(&i8259_syscore_ops); + + return 0; +} +device_initcall(i8259A_init_ops); + +void __init legacy_pic_pcat_compat(void) +{ + pcat_compat = true; +} |